1. Field of the Invention
The present invention relates generally to the field of ground level concrete tanks which are used primarily to hold water, and in particular the present invention relates to plastic lined concrete tanks equipped with waterstop systems to inhibit penetration and leakage of the contents of the tank between the tank foundation and the bottom edge of an upright wall.
2. The Prior Art Background
Waterstop systems are well known standard materials used in the ground level concrete tank construction industry to prevent the contents such as water, etc. from penetrating through the joints at the base of the tank where the walls meet the floor. Normally, waterstop systems are anchored directly in the concrete or adhered or fastened directly to the surface of the concrete in concrete structures. Known waterstop systems recognize the fact that concrete structures can experience significant movement at the joints, for example, the joint between the bottom edge of an upright wall and the floor, in response to changes in liquid level, climatic cycles, environmental changes and the like, and so waterstop systems are commonly made from various types of plastic and rubber for flexibility. However, in the case of plastic lined concrete tanks, there has been no good solution to problems encountered particularly when a waterstop system is anchored in the concrete floor and then must be permanently sealed to a plastic lining on a tank wall to prevent leakage. The problem is that the tank walls cycle (expand and contract) with changes in temperature and liquid levels in the tank, and the waterstop system must contort to accommodate the resultant movement. Such contortion often ruptures or otherwise violates (i.e., compromises the projected lifespan of) the primary seal between the lining and the waterstop system.
In addition, with known tank lining systems, plastic floor liners must generally be secured at their peripheral edges using bolts or other forms of fastening. This is expensive and often unreliable, since the bolts must be gasketed with another material, generally a foamed rubber, to make them watertight.